Method for manufacturing high tensile strength steel plate
US7648597B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 6, 2005 |
| Grant date | Jan 19, 2010 |
| Priority date | — |
| Expiry date | Jul 24, 2026 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22C38/06
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention provides a method for manufacturing high tensile strength steel plate having 570 MPa (N/mm2) or larger tensile strength and having also extremely superior balance of strength and toughness both before PWHT and after PWHT to that of the conventional steel plates, by specifically specifying the temperature-rising rate at the plate thickness center portion of a quenched and tempered material during tempering, and to be concrete, the method has the steps of: casting a steel consisting essentially of 0.02 to 0.18% C, 0.05 to 0.5% Si, 0.5 to 2.0% Mn, 0.005 to 0.1% Al, 0.0005 to 0.008% N, 0.03% or less P, 0.03% or less S, by mass, and balance of Fe and inevitable impurities; hot-rolling the cast steel without cooling the steel to the Ar3 transformation point or lower temperature, or after reheating the steel to the Ac3 transformation point or higher temperature, to a specified plate thickness; cooling the steel by direct quenching from the Ar3 transformation point or higher temperature, or by accelerated cooling, to 400° C. or lower temperature; and then tempering the steel, using a heating apparatus being installed directly connecting the manufacturing line containi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.